Interlock circuit for utility vehicle park brake

Abstract

An interlock circuit for a utility vehicle park brake includes a relay connected to neutral switch on a transmission. The relay is actuated by electric current to move a contact to a closed position if the neutral switch is out of neutral. A throttle pedal switch connected to the relay moves a contact to a closed position if the throttle pedal is depressed. A park brake switch connected to the throttle pedal switch moves a contact to a closed position if the park brake is engaged. Closing all of the contacts grounds an ignition circuit connected to the interlock circuit, which may be a magneto ignition circuit.

1. An interlock circuit for a utility vehicle park brake, comprising:
 a normally open neutral switch moving to a closed position if a transmission of the utility vehicle is in neutral; 
 a park brake interlock relay connected to the neutral switch and moving to a closed position if the neutral switch is open; 
 a normally open throttle pedal switch connected to the park brake interlock relay and moving to a closed position if a throttle pedal is depressed; 
 a normally open park brake switch connected to the throttle pedal switch and moving to a closed position if the park brake is engaged; and 
 the park brake switch connected to an ignition circuit that provides a high voltage to a spark plug unless the ignition circuit is grounded because the park brake switch, the throttle pedal switch and the park brake interlock relay are all closed. 
 
     
     
       2. The interlock circuit of  claim 1  wherein the ignition circuit includes a transistor connected to a primary coil. 
     
     
       3. The interlock circuit of  claim 1  wherein the ignition circuit provides the high voltage to the spark plug if at least one of the park brake switch, the throttle pedal switch and the park brake interlock relay are open within a pre-specified time after being closed. 
     
     
       4. An interlock circuit for a utility vehicle park brake, comprising:
 a park brake switch connected to a throttle pedal switch connected to a park brake interlock relay; the park brake switch, throttle pedal switch and park brake interlock relay grounding a magneto ignition circuit if the relay and switches are all closed; the interlock relay being closed by placing a transmission in neutral. 
 
     
     
       5. The interlock circuit of  claim 4  further comprising a normally open neutral switch connected to the interlock relay. 
     
     
       6. An interlock circuit for a utility vehicle park brake, comprising:
 a relay connected to a neutral switch on a transmission; the relay actuated by electric current to move a contact to a closed position if the neutral switch is out of neutral; 
 a throttle pedal switch connected to the relay and moving a contact to a closed position if the throttle pedal is depressed; 
 a park brake switch connected to the throttle pedal switch and moving a contact to a closed position if the park brake is engaged; 
 the closing of all of the contacts grounding an ignition circuit. 
 
     
     
       7. The interlock circuit of  claim 6  wherein the ignition circuit is a magneto ignition circuit. 
     
     
       8. The interlock circuit of  claim 6  wherein the throttle pedal switch and park brake switch are biased to an open position.